The present invention relates to a composition for use in a washing machine and to a process for the use thereof.
Although modern washing machines usually have numerous different washing programs, which differ with respect to the duration and temperature of the individual washing and rinsing cycles, a washing programs essentially comprise the following basic steps: prewashing cycle, main washing cycle, several rinsing cycles and spinning cycle. Whilst the actual detergent which is intended to give rise to the cleaning action is added at the start of the main washing cycle (or optionally at the start of the prewashing cycle), during the rinsing cycles special agents with different functions can be used. These special agents for the rinsing cycles are intended to mainly bring about further advantages for the washing treatment. A non-exhaustive list of such agents and without restriction thereto comprises fragrances (pleasant smell of the washing), fabric softeners (softness of the washing), antistatic agents reduction or prevention of the build-up of static electricity in the washing), agents for restoring the capacity of the washing to absorb moisture, mild acids (beaking down incrustations or neutralization of alkalinity), bleaches, either having an oxygen or a chlorine base (improving the cleaning action), disinfectants, agents for a persistent protection of both the washing and the person wearing the latter against insects or cites, agents for an improved removal of grease marks, finishing agents giving a protection against creasing, optical brighteners, ironing auxiliaries (to facilitate ironing of the washing), agents for inhibiting dye transfer, enzymes such as cellulases, lipases, etc. for special uses.
The described different functionalities have hitherto been achieved (if at all) by charging different products, partly via separate dosing or charging devices, as well as charging at different times.
The aim of the present invention was to combine within a single product the cleaning function and the function or functions of the substance or substances to be added during the rinsing cycles, with a constant efficiency compared with the results achievable with a separate dosing or charging, or to permit the charging of further substances in the rinsing cycles. DE-OS 20 65 153 and DE-OS 20 07 413 disclose detergent pellets for use as washing agents, in which it is inter alia provided to combine two components with different functionalities. The structure is formed from a covering or enveloping shell, which is e.g. formed from two shell halves, which comprise a cleaning agent, and a cavity surrounded by the shells and which contains additives such as softeners, brighteners, etc.
British patent 1 390 503 discloses a liquid cleaning agent or detergent which contains capsules, which are insoluble in the composition, but release their content when the composition is diluted with water. This objective is achieved in that the capsules are coated with a substance, which has a poor solubility in water solutions with a high ionic strength, but which is soluble if the ionic strength is reduced by dilution. It is pointed out that this procedure can be used in order to incorporate materials into the liquid cleaning agent, which in the latter are unstable or would produce an instability if added directly. It is also proposed to use this procedure for delaying the release of a specific substance. Reference is made to use in detergents. The encapsulated material is released within two minutes following the dilution of the cleaning agent with water, i.e. during the main washing cycle.
U.S. Pat. No. 4,082,678 describes a fabric conditioner, which comprises a closed container containing a releasable agent and which is used for making water-insoluble or non-dispersible an inner container located in the first container and which is normally water-soluble or water-dispersible, the inner container containing a fabric conditioner. The inner container comprises a substance, whose solubility in water is highly dependent on the ionic strength or the pH-value of the medium and the agent used for rendering the inner container insoluble is an agent for controlling the pH-value or the ionic strength.
Japanese patent applications KOKAI 60-141705, 61-28440, 61-28441, 61-28596, 61-28597 and 61-28598 describe processes for the production of pH-sensitive microcapsules for use in detergents. The pH-sensitive coating is a copolymer of the following monomers:
A) at least one basic monomer of formula I: 
xe2x80x83in which R is hydrogen or a methyl group and R1 and R2 in each case an alkyl group with 1 to 3 carbon atoms and x is an integer from 1 to 4,
B) at least one monomer which is insoluble or difficultly soluble in water and
C) at least one water-soluble monomer.
It is pointed out that the described polymers are insoluble at a pH-value of 9.5 or higher and are soluble at a pH-value of 8.5 or lower. Different ingredients of cleaning agent compositions are described, which can be successfully and usefully coated with, the described polymers. The aim of the invention described therein is to protect substances, which only evolve their function during the rinsing process up to the start of the latter and then to release them as immediately as possible. A disadvantage of the solution described in these Japanese patent applications is that the enveloped particles are in direct contact with non-alkaline washing water at the start of the washing cycle, which can give rise to a partial dissolving of the protective covering.
Japanese patent KOKAI 50-77406 discloses a washing aid, which is surrounded by a water-soluble covering or envelope, obtained by mixing polyvinyl acetal dialkyl aminoacetate and at least one organic acid, which is solid at room temperature. This protective envelope is intended to protect the washing aid during the main washing cycle one to release it during rinsing cycles. The described compound reacts to the pH-value change between the main washing cycle and the rinsing cycle. Here again the disadvantage exists of a possible partial dissolving of the protective envelope at the start of the washing cycle.
European patent applications EP 284 191 A2 and EP 284 334 A2 disclose a water-soluble polymer film for releasing washing additives during the rinsing cycle of washing machines, remaining intact during the normal washing cycle over a range of typical temperatures and rapidly dissolving during the rinsing cycle. These applications point out that the use of pH-sensitive coatings was admittedly known, but that these films are normally also temperature-sensitive, so that they do not remain reliably stable during the different temperatures of the washing cycle. The solution proposed is a pH-dependent material (which undesirably also has a positive, temperature-dependent dissolving behaviour) which is combined with a material having a negative, temperature-dependent dissolving behaviour. This combination is supposed to guarantee that the coatings do not dissolve at the high temperatures at the start of the washing cycle (in particular the very high temperatures occurring in American machines).
European patent application EP 481 547 A1 discloses multilayer dishwashing machine tablets having a core, a separating layer surrounding the core and an outer layer for the sequential release of the ingredients of the different layers. This tablet is fundamentally intended to solve two problems, namely
1) incompatible materials can be formulated together in a single tablet and released at different times in order to avoid mutual influencing and
2) compositions, which are intended to evolve their functions at different times, can be formulated in a single tablet.
An essential disadvantage of this prior art is that for initiating dissolving of the covering layer the temperature is used as the initiating factor, i.e. temperature-sensitive materials are used for the covering material. As the temperature/time pattern in washing machines can differ very considerably as a function of the selected program it would be difficult, if not impossible, to select a material for the covering which is usable for all possible programs of modern washing machines. EP 481 547 A1 admits (p 7, lines 37 to 43) that the choice of the material of the covering layer must take account of equipment and program-specific features. Thus, there is a clear limitation to he practical usability of the products described. The citation makes to mention of a use for washing machines.
PCT application WO 95/29982 discloses a dishwashing agent with a delayed release of a clear rinsing agent in the form of a nonionic surfactant, which together with an inorganic builder salt forms a core particle, which is provided with a wax-like covering in order to ensure the delayed release. This covering is a substance which does not melt at the operating temperatures encountered during the cleaning cycle, but which at alkaline pH-values is so gradually chemically disintegrated that there is still an effective clear rinsing agent quantity present at the end of the main cleaning cycle and is transferred into the rinse clear cycle. The citation makes no mention of a use for washing machines.
A disadvantage of the solution described in this citation is that the covering is rendered soluble by chemical saponification at alkaline pH-values, so that the time at which the clear rinsing substance is released from the core is a function both of the temperature and the length of the main cleaning cycle. The patent application provides no teaching as to how a product is to be formulated with which the clear rinsing agent can be released in the rinsing cycle in all washing programs of any random equipment type. Finally the product is a mixture of granular cleaning agents and granular clear rinsing particles.
In view of the prior art, the problem of the present invention is to provide a composition according to the preamble, which is usable for most washing programs of different washing machine types and in each of the said cases only releases the substance or substances intended to exert their action substantially firstly in the rinsing cycles only in said cycles. The aim is to achieve this without any significant restriction regarding the choice of detergents used, the substance or substances used for the rinsing cycles and other constituents of the composition.
According to the invention this problem is solved with a composition according to the preamble, which is characterized by a basic composition evolving its function essentially in the main washing cycle of the washing machine, and at least one particle with at least one core incorporating at least one substance, which evolves its function essentially in the rinsing cycles of the washing machine, and a covering substantially completely surrounding the core or cores, which comprises at least one compound, whose solubility increases with decreasing concentration of a specific compound in the surrounding medium, agents being provided so as to prevent up to the start of the rinsing cycles any significant dissolving of the covering or significant detachment of the covering from the core or cores.
In an advantageous embodiment the concentration of the specific compound in the local environment of the particle or particles is sufficiently high up to the start of the rinsing cycles to prevent up to this time a significant dissolving of the covering and a significant detachment of the covering from the core or cores.
Preferably the particles are coated with a substance which, substantially independently of the concentration of the specific compound in the surrounding medium, is dissolved or separated during the rinsing cycles of the washing machine.
Preferably the basic composition is in the form of a tablet.
An embodiment of the invention proposes that at least one particle is so placed in or on the tablet that the concentration of the specific compound in the local environment of the particle or particles is sufficiently high up to a substantially complete dissolving of the tablet in order to prevent a significant dissolving of the covering or a significant detachment of the covering from the core or cores.
Preferably the or all the particles are received in at least one cavity of the tablet completely surrounded by the basic composition.
At least one cavity contains one or more particles, which alone or together substantially have the same volume as the cavity.
Preferably at least one cavity has a larger volume than the or all the particles received in the particular cavity.
In an alternative of the invention the particle or particles are loosely located in the interior of the cavity.
In another alternative the particle or particles are fixed in the interior of the cavity, preferably by an adhesive.
In a further embodiment the cavity is substantially centrally placed in the interior of the tablet.
The invention also proposes that -he tablet has a single, substantially spherical cavity.
According to the invention it is preferable to receive in the cavity a single, substantially spherical particle, whose external diameter is smaller than the internal diameter of the cavity.
In a further embodiment the or all the particles are received in at least one tablet cavity, which is only partly surrounded by the basic composition.
Preferably the cavity is a depression in one of the tablet surfaces in which the particle or particles are at least partly received.
In a preferred embodiment the particle or particles are so received in the cavity or depression that they do not project over the surface or surfaces of the tablet.
In a special embodiment, the invention proposes that the cavity or depression only contains a single tablet, whose volume and shape in the vicinity of the cavity or depression substantially coincides with the volume and shape of the cavity or depression and substantially completely fills the same.
Preferably the cavity or depression has a substantially circular cross-section face parallel to one of the surfaces to which it opens or in which it is placed.
The invention also proposes that the cavity or depression only opens to such an extent towards the surface or surfaces that the particle or particles received therein cannot pass through the opening or openings of the cavity or depression.
Preferably the particle or particles are loosely arranged in the cavity or depression.
In another alternative the particle or particles are fixed in the cavity or depression, fixing preferably taking place with an adhesive.
In an embodiment of the invention, the basic composition comprises at least one composition selected from the group comprising a detergent composition, a water softener composition and a washing intensifier composition.
In a preferred embodiment of the invention, the covering comprises at least one compound, which at the concentration of the specific ion at the end of the main washing cycle of the washing machine is not or is only slightly soluble and at the concentration of the specific ion in the rinsing cycles has such a sufficient solubility that it is so substantially dissolved in the rinsing cycles or detached from the core or cores that an at least partial escape of the core material into the medium of the rinsing cycles is permitted.
Preferably the solubility of the compound increases with decreasing OHxe2x88x92 ionic concentration and therefore decreasing pH-value in the surrounding medium.
In particularly preferred manner the compound has at a pH-value above 10 no or only a limited solubility and at a pH-value below 9 such an adequate solubility that it is so substantially dissolved in the rinsing cycles or is so detached from the core or cores that an at least partial escape of the core material into the medium of the rinsing cycles is permitted.
Preferably this compound comprises a polymer, in particularly preferred manner a pH-sensitive polymer, which comprises at least one repeat unit, which has at least one basic function, which is not part of the backbone chain of the polymer.
In a preferred embodiment the polymer comprises at least one repeat unit, which is based on a compound selected from the group comprising vinyl alcohol derivatives, acrylates or alkyl acrylates having said basic function.
According to the invention the polymer is a carbohydrate functionalized with said basic function.
The aforementioned basic function is preferably an amine, in particularly preferred manner a secondary or tertiary amine.
According to a preferred alternative the repeat unit is based on a compound having the following formula III: 
in which G is a linking group selected from xe2x80x94COOxe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, xe2x80x94NHCONHxe2x80x94, xe2x80x94NHCOOxe2x80x94, xe2x80x94OCONHxe2x80x94or xe2x80x94OCOOxe2x80x94, R1 independently of one another being hydrogen or an alkyl group with 1 to 3 carbon atoms, R2 independently of one another hydrogen or an alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to 6.
Preferably the repeat unit is based on a compound with the following formula IV: 
in which R1 independently of one another is hydrogen or am alkyl group with 1 to 3 carbon atoms, R2 independently of one another hydrogen or an alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to 6.
According to another embodiment of the invention the basic function is an imine or a basic, aromatic N-containing group, preferably a pyridine group or an imidazole group.
According to a further embodiment the pH-sensitive polymer is a polymer derived from chitosan.
The invention finally proposes that the compound comprises K-carrageenan.
According to an embodiment of the invention the core or cores comprise at least one material selected from the group consisting of fragrances, fabric softeners, antistatic agents, agents for restoring the capacity of washing to absorb moisture, mild acids, bleaches, disinfectants, agents for persistent protection of both the washing and the person wearing it against insects or mites, agents for the improved removal of grease marks, agents for finishing with protection against creasing, optical brighteners, ironing auxiliaries, agents for inhibiting dye transfers and enzymes.
In an alternative the core or at least part of the cores can be in the form of an encapsulated liquid. In another embodiment the core or at least part of the cores is in solid form.
The invention also relates to a process for performing a washing cycle in a washing machine, in which the composition according to the invention is added at a suitable time during the prewashing cycle or main washing cycle to the medium located in the washing machine.
In a special embodiment of this process for the case that the basic composition in the form of a tablet is unable, following its dissolving in the medium to make available therein a concentration of the specific ion, up to the end of the main washing cycle, which is sufficiently high in order to prevent a substantial dissolving of the covering and a substantial detachment of the covering from the core or cores, said adequate concentration of the specific ion is brought about by he addition of a further composition, such as e.g. a detergent composition, to the medium of the main washing cycle at an appropriate time.
The composition according to the invention is characterized in that it delivers excellent results both in the main washing cycle and in the rinsing cycles of a washing machine. The basic composition e.g. in the form of a tablet is dissolved during the main washing cycle and can evolve its corresponding, intended action (cleaning, water softening, washing intensification, etc.). The particle according to the invention contains as the core material the substance or substances having to evolve their main function in the rinsing cycles of the washing machine. Said substance or substances are protected by a covering which, at the concentration of the specific compound, e.g. the pH-value, and the temperature of the main washing cycle, is stable and dissolves or is detached either insignificantly or not at all.
Following the main washing cycle and the pumping out of the washing liquor a dilution effect occurs in the rinsing cycles through the repeated entry of fresh water, so that the concentration of the specific compound drops significantly. Obviously the actual course of this concentration change in the washing cycle of a washing machine is greatly dependent on the composition of the detergent used. The following table 1 shows in exemplified manner a pH-profile measured in the case of a CANDY Activa 80
Plus washing machine, with a 60xc2x0 washing program with 3 kg of fabrics having a normal dirtiness level and 3 standard 40 g detergent tablets, as described in detail hereinafter (example 4 ).
It is clear throughout the main washing cycle there is a relatively high pH-value of 10.25 to 10.35, which by the fourth rinsing cycle has dropped to 8.50. The solubility of the covering material must consequently be reduced to such an extent at pH-values of preferably below 9 that it rapidly dissolves or is detached and that the effective core material is released into the surrounding medium, i.e. the rinsing water.
It is essential that the protection of the core material is effective from the addition to the composition according to the invention to the water up to the start of the rinsing cycles, i.e. also before the washing liquor reaches a sufficiently high concentration of the specific compound, as will be explained hereinafter.
As an alternative to the preferably used tablet form of the basic composition other administration forms are possible and covered by the protective scope of the present invention. Thus, the particles with the covering variable in its solubility in response to a change in the concentration of the specific composition can be connected by a granulation or similar process to the basic composition, can e.g. be enveloped. In order to ensure for the said embodiment an optionally desired reduced contact between the covering and the basic composition, the particles can be surrounded with a further protective jacket, which e.g. comprises a compound soluble in water independently of the concentration of the specific compound. With this embodiment during the main washing cycle once again firstly the basic composition and the protective jacket of the particles were dissolved and once again the particles protected by the covering according to the invention were left behind.
Provided that there is to be no charging by special dosing aids able to retain the particles according to the invention, the particles according to the invention must be chosen sufficiently large that they are not discharged to a significant extent during pumping out of the washing machine following the main washing cycle and the first rinsing cycles or charging by charging devices.